Microsoft has now started rolling out the Windows 10 Fall Creators Update (build 16299.15) to Insiders in the Release Preview ring, confirming our original report that build 16299.15 is indeed the RTM (Release To Manufacturing) build of the Fall Creators Update.

Insiders in the Release Preview ring should expect a larger than usual update, as this is the entirety of the Fall Creators Update being downloaded and installed. Microsoft is testing the upgrade path from the Creators Update to the Fall Creators Update with Insiders in the Release Preview before official rollout on October 17.

As part of final preparations for the general availability of the Windows 10 Fall Creators Update on Oct. 17th, we have begun releasing Build 16299.15 to Windows Insiders in the Release Preview ring.

Microsoft says that this build is rolling out slowly, so if you're in the Release Preview ring and don't yet see this update, be patient! This update should be available to you very soon. In the meantime, if you aren't yet ready to upgrade to the Fall Creators Update, make sure you leave the Insider Program to avoid getting upgraded.

The Release Preview ring is the very last ring a build goes to for testing before it rolls out to the public. This is why a build moving to the Release Preview ring is significant. It means that this build is going to eventually roll out publicly, and that it needs to be tested with a wider group of Insiders before going live.

If you're in the Release Preview ring and haven't been keeping track of all the new changes Microsoft has been working on over the last few months, check out our complete changelog for the Fall Creators Update. Build 16299.15 will be giving you all those new features and enhancements to enjoy.

Are you in the Release Preview ring? Let us know if you're getting the update to the Windows 10 Fall Creators Update build 16299.15 already.